Cephalometric effects of face mask/expansion therapy in Class III children: A comparison of three age groups,☆☆,,★★,

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Abstract

The purpose of this investigation was to determine the skeletal, dental, and soft tissue effects of face mask/expansion therapy and to examine the effect of age on treatment response. Pretreatment and posttreatment cephalometric radiographs from 63 subjects (4 to 13 years) who had a Class III malocclusion were analyzed. Serial cephalometric tracings of 32 subjects with Class I occlusion made at 4, 6, 8, 10, 12, and 14 years were used as controls. Landmarks were digitized on each tracing and treatment effects were measured by using cranial base and maxillary superimposition techniques. Annual rate differences were compared with t tests for the combined treated group (N = 63) and between stratified treated groups (4 to 7 years N = 15, 7 to 10 years N = 32, 10 to 14 years N = 16). The treated group (N = 63) demonstrated significant (p < 0.001) hard and soft tissue changes that resulted from treatment. Skeletal change was primarily a result of anterior and vertical movement of the maxillae. Mandibular position was directed in a downward and backward vector. Orthodontic changes contributed to the correction, and soft tissue effects resulted in a more convex profile. Minimal significant differences were observed between age groups when comparing angular and linear measurements alone. However, when analyzing the algebraic sum of treatment effects (Johnston analysis), significantly (p < 0.01) greater differences were observed in apical base change (ABCH) and total molar correction (6/6) in the younger age groups. This study demonstrates that face mask/expansion therapy produces dentofacial changes that combine to improve the Class III malocclusion. Although early treatment may be most effective, face mask therapy can provide a viable option for older children as well.(Am J Orthod Dentofacial Orthop 1998;113:12)

Section snippets

Materials And Methods

The sample consisted of 63 subjects, 38 female and 25 male, and was collected based on these criteria: (1) Pretreatment (mean 8.0 years) and posttreatment (mean 8.8 years) lateral cephalograms made on the same cephalostat and of good quality; (2) a developing Class III malocclusion identified by a combination of an ANB measurement of less than 1°, 40 a convexity measurement of less than 1 mm,41 a Wit's 42 denture base relationship of zero or less, an edge-to-edge incisor relation or anterior

Results

The annualized means and standard errors for all the measured values are given in Tables I through V and Fig. 2.

. Pitchfork diagrams showing differences among age groups in functional occlusal plane analysis (Johnston analysis).

Table I summarizes the mean changes in traditional cephalometric measurements.

. Traditional cephalometric measures; changes for the treated and control groups

VariablesCombined treatedCombined controlTreated 4-7Control 4-7Treated 7-10Control 7-10Treated 10-14Control 10-14
Empty CellMeanEmpty Cell

Error Study

Dahlberg's formula53was used to determine the error standard deviations for the variables in each data set. Five treated subjects (five T1 and five T2 cephalograms) were selected at random. Each cephalogram was retraced, superimposed, and digitized and the error determined. For the conventional measures, linear measurements had error of less than 1 mm and angular measurements had an average error of 1.5°. The average error in the x-y coordinate data was slightly greater, but still did not

Discussion

The current study demonstrated a significant response to face mask/expansion therapy, which affected many areas of the dentofacial complex. Skeletal change was primarily a result of anterior and vertical movement of the maxillae. When maxillary change was compared as an annual rate and normal growth (control) subtracted, the results confirmed a true maxillary orthopedic effect resulting from treatment (SNA +2.51°, nasion ⊥ A point +1.96 mm, A point +2.39 mm). Other investigators11, 25have

Conclusion

Correction of a Class III malocclusion with face mask/expansion therapy appears to result from a combination of skeletal and dental changes that produce an improvement in the soft tissue profile. The treated group ( N = 63) demonstrated statistically significant hard and soft tissue movements affecting the entire dentofacial complex. Skeletal change was primarily a result of anterior and vertical movement of the maxillae. Mandibular position was directed backward and downward but with a minimal

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  • Cited by (0)

    aIn partial fulfillment of the requirements for certificates in Orthodontics and Pediatric Dentistry at the University of California at Los Angeles.

    ☆☆

    bProfessor and Chair, Orthodontic Department, University of Southern California.

    cProfessor and Chair, Section of Orthodontics, School of Dentistry at the University of California at Los Angeles.

    ★★

    Reprint requests to: Dr. Andrew J. Kapust, 344 Cleveland Ave., Olympia, WA 98501.

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